Characterizing Human Peripheral Blood Lymphocyte Phenotypes and Their Correlations with Body Composition in Normal-Weight, Overweight, and Obese Healthy Young Adults

Abstract

Background and Objectives: Obesity-associated chronic low-grade inflammation supports various systemic alterations. In this descriptive study, 122 apparently healthy adults aged 20 to 35 years were voluntarily included and classified based on body mass index (BMI) as normal-weight (NW), overweight (OW), and obese (OB). This study aims to characterize peripheral blood (PB) lymphocyte (Ly) phenotypes and investigate their correlations with body composition indices (BCIs) in healthy young adults. Materials and Methods: The following BCIs were measured: waist circumference, hip circumference, height, waist-to-hip ratio, waist-to-height ratio, total body fat mass, visceral fat level, weight, and BMI. White blood cell count (WBC), Ly absolute count, serum TNF-α, and IFN-γ were quantified. Ly subpopulations were analyzed as follows: total TLy (TTLy—CD45+CD3+), early activated TLy (EATLy—CD45+3+69+), total NKLy (TNKLy—CD45+CD3−CD56+CD16+), NKdim (low expression of CD56+), NKbright (high expression of CD56+), BLy (CD45+CD3−CD19+), T helper Ly (ThLy—CD45+CD3+CD4+), and T cytotoxic Ly (TcLy—CD45+CD3+CD8+). Results: Higher BMI has significantly higher WBC and BLy (p < 0.0001; p = 0.0085). EATLy significantly decreased from NW to OB (3.10—NW, 1.10—OW, 0.85—OB, p < 0.0001). Only EATLy exhibited significant negative correlations with all the BCIs. A significantly higher TNF-α was observed in the OW and OB groups compared to the NW group. IFN-γ increased linearly but nonsignificantly with BMI. TTLy showed a nonsignificant positive correlation with both IFN-γ and TNF-α, while EATLy showed a negative correlation, significant only for IFN-γ. NKLy subpopulations exhibited a consistent negative correlation with TNF-α, significant only for NKdim (p = 0.0423), and a nonsignificant consistent positive correlation with IFN-γ. A nonsignificant negative correlation between age and both TNKLy (r = −0.0927) and NKdim (r = −0.0893) cells was found, while a positive correlation was found with NKbright (r = 0.0583). Conclusions: In conclusion, the baseline immunological profile of PB is influenced by excessive adipose tissue in healthy young adults.